1. Field of the Invention
The present invention relates to a clutch device used in an automatic transmission for an automobile.
2. Description of the Related Art
In an automatic transmission used in an automobile, plural planetary gearsets are used. In this type of automatic transmission, plural clutch devices are used to perform gear shifting by changing the connections between the elements of the planetary gearsets.
To change from one gear ratio to the next gear ratio, for example, operations to rotate elements which were stationary before the shift, or to lock elements which were rotating before the shift, or to reverse the direction of the rotation of an element are required.
Therefore, a one-way clutch has been used to synchronize the engaging time of one clutch device with the disengaging time of another clutch device to carry out smooth shifting from the first gear to the second gear, a brake for locking the free-running function of the one-way clutch to attain engine braking in the first gear, another one-way clutch to synchronize the engaging time of one clutch device and the disengaging time of another clutch device to carry out smooth shifting from the second gear to the third gear, and another brake for locking the free running function of the latter one-way clutch to attain engine braking in the second gear (New Car Features of domestic TOYOTA CORONA FF Coupe, 4 Door Sedan, 5 Door, August 1985).
Thus, one-way clutches are required only for synchronizing the engaging time of one clutch device with the disengaging time of another clutch device, and it caused an increase of axial length, weight and cost.